Process for treating oils



May 25, 193?. u. B. BRAY r AL PROCESS FOR TREATING OILS Original FiledAug. 4, 1931 atented` ay 25, i937 PROCESS FOR TREATING OILS Originalapplication August 4, 1931, Serial No.

555,019. Divided and this application February 5, 1934, Serial No.709,836

9 claims.

This invention relates toV a process for treating petroleum to producelubricating oil and is a division of our copending application SerialNo. 555,017, filed August 4th, 1931. More particularly, the inventionrelates to the separation of asphalt from oil.

It is an object of our invention to separate asphalt from oil by meansof a solvent at an elevated temperature. A further object of ourinvention is to separate the asphalt from gil by means of liqueednormally gaseous hydrocarbon solvents, such as liquid propane, attemperatures above ordinary room or normal temperaturesand undersuperatmospheric pressure.

Itis another object of our invention to separate the asphalt from oilsat temperatures above 75 F. and more particularly at temperatures ofapproximately 120 F.

Another object of our invention is to separate wax from oils containingthe same subsequent to de-asphaltizing the oil at elevated temperatures.To separate the wax, We prefer to vaporize a portion of the solventunder reduced pressure. This will chill the oil and cause the Wax toprecipitate from solution.

A further object olf our invention is to treat the oil with chemicals,such as sulphuric acid and clay, in the presence of a solvent subsequentto deasphaltizing at elevated temperatures and also to separate the oilinto parafnoid and non-paraflinoid fractions by means of a selectivesolvent, such' as liquid sulphur dioxide.

Itis another object to effect the separation or extraction of the oilsubsequent to deasphaltizing either in the presence or substantialabsence of a diluent as liquid propane.

Other objects and features of our invention will be understood byreferring to the drawing which represents a schematic arrangement of oneform of apparatus in which our process may be carried out.

Referring more particularly to the drawing,

crude oil from which all of the gasoline, kerosene and gas oil has beenremoved in tank I is with- 4 drawn through valve 2 and sent by means ofpump I un 3 to line 4 where it meets a stream of solvent corn-4 ing fromstorage tank II through valve `I2 pump I3 and line I4. A solvent ischosen which is capable of dissolving the oil and wax but which does notdissolve the asphalt. As solvents, ,we may employ light petroleumfractions,'such as naphtha, casinghead gasoline and petroleum fractionsnormally vaporousl vat ordinary temperature and` pressure'. Othersolvents which may be used are (ICI. ISS-13) alcohol, ether, mixtures ofalcohol and ether,

acetone, etc. We prefer to use as our solvent a liquefied normallygaseous hydrocarbon such as a petroleum fraction obtained by therectiiication of natural gasoline. Such solvents comprise methane,ethane, propane, butano or mixtures thereof. A typical analysis of sucha fraction` is 6.72% ethane, '72.2% propane, 19.91% isobutane and `1.17%normal butane. This fraction is liquid at ordinary temperatures at apressure of about lbs. per square inch.

The mixture of topped crude and liqueed normally gaseous hydrocarbonsolvent, such as liquid propane under pressure, passes into chiller 5where the mass is cooled by allowing a portion of the liquid propane tovaporize under reduced pressure through valve 6 intoy line l. Thevaporized ,propane in line 'I is compressed by compressor 8 and sent tocondenser 9 where it is liqueed and passes by means of line I0 to pro-4pane storage tank I I. The cooled mass of topped crude and liquidpropane in chiller 5' passes by means of line I5 to agitator I6 Where itis thoroughly mixed, after which it passes by means of line I1 todecanter I8 Where the asphalt settles out.

The asphalt in decanter I8 is removed through Valve I9 and sent by pump20 through line 2| to heater 22 where the temperature ofthe mass israised suiiciently to vaporize all of the propane '30 and moisturepresent. The heatedv mass then passes by means of line 23 into separator24 l where the asphalt separates out and is removed through valve 25 andline 26 to storage tank 21. The mixture of Water vapor and propanepasses from separator 24 through line 28 to condenser 29 where the watervapor is condensed. The mixture of Water and propane vapor passes fromcondenser 29 to separator 30 where the Water is separated' out and isremoved through valve 3l and line 32. The propane vapor in separator 30passes by means of line 33 to cornpressor 34 Where it is compressed andsent by means of lines 33 and,'l2 to condenser 9 where it is liquefiedand' passes through lline I0 to Vstorage tank II.

The propane solution of oil in decanter I8 is withdrawn through line 35and passes into chiller -36 where the temperature of the mass is loweredto a point sumcient to cause thorough'wax preo cipitation by allowing aportion of the propane present in chiller 36 to vaporize under reducedpressure through valve 31 into line 38. The propane vapor in line 38 iscompressed by compressor 39 and.sent through lines 38 and 12' 55 sulphurdioxide present.

stage 43 into line 44 whereit is mixed with sulphuric acid coming fromtank 45 through valve 46, line 41, pump 48 and line 41'. The mixture ofoil and acid then passes into agitator 49 where it is thoroughly mixed,after which it passes into decanter 5| where the` sludge is allowed tosettle out. rThe sludge in decanter 5| is removed through valve 53 andsent by means of pump 54 through line 55 to heater 56 where thetemperature of the mass is raised sufficiently to vaporize the propane.The heated mass then passes by means of line 51 to separator 58 wherethe sludge separates out and is withdrawn through valve 59 and line 00.The propane vapor passes from separator 58 through line 6| to scrubbingtower 62 where it is contacted with liquid caustic soda to remove anyThe scrubbed propane passes from tower 62 throughvalve 88, line 61,compressor 88, lines 81' and 12' to condenser 9 where it is liqueed andpasses by means of line I0 to storagel tank The acid treated oildissolved in propane in decanter 5| passes by means lof line 52 to claytower |25 where any remaining sludge iseremoved. The propane solution oftreated oil then passes from tower |25 by meansolline 69 to evaporator10 where the propane present is vaporized with the aid of steamintroduced through closed steam coil 14. The propane vapor passes fromevaporator 10 through valve 1| into line 12 thence to compressor 13where it is compressed and sent by means of line 12' lto condenser 9ywhere it is liquefied Vand passes by means of line |20 to storage tankil.

'I'he propane free oil in evaporator 10 is withdrawn through valve 15and passes through cooler 10 where the temperature is loweredsuiiiciently for extraction with a selective solvent such as liquidsulphur dioxide which is adapted to separate the oil into parafnoid andnon-paraiinoid fractions. The cooled oil passes from cooler 16 y to pump11 which forces it through line 18 into ing the non-paramnoid fractionswhich are removed in the form of a sulphur-dioxide solution throughvalve 94 into line 95 from Which the mixture passes into evaporator 96where the sulphur dioxide present is removed with the aid of steamintroduced into closed steam coil |05 passes through valve 91 into line90 and thence to compressor |0l where it is compressed and passes bymeans of line ,90' to condenser |02 where it is liqueiied and passes bymeans of line |03 to sulphur dioxide storage 19. The sulphur dioxidefree ou 1n evaporator 9s is withdrawn through valve 98 and passes bymeans of line 9 9 to storage tank |00.

'I'he ascending column of oil in column |04 from which there has beenremoved the sulphur dioxide soluble constituents, passes throughvalve'83 and line 84 into auxiliary settling chamber 85 where anyremaining liquid sulphur dioxide settles out. The settled oil fromchamber 85 passes through line 81 into4 evaporator 88 where the sulphurdioxide present is vaporized by aid of steam introduced into closedsteam coil |06 and passes through Valve 89 to line 90 and thence tocompressor |0| where it is liqueiied and passes by means of line |03 tosulphur dioxide storage tank 19. The sulphur dioxide free oil inevaporator 88 is withdrawn through valve 9| and-sent by means ofiine 92to refined oil storage tank 93.

Instead of employing liquid sulphur dioxide asa selective solvent forseparating the oil into paraf- `iinoid and non-parafnoid oils, we mayemploy as solventagents which will eiect this separation, mixtures ofacetone and benzol, aniline or methyl formate. However, liquid sulphurdioxide has of liquid sulphur dioxide, it is possible to separate,

this material into oils which have a low temperature viscositysusceptibility and oils which have a high temperature viscositysusceptibility.

As illustrative of the operation of the process for one .type of oilwithout intending to limit our invention, the following is an example:

The topped oiLin tank l, at a temperature approximating 200 F., is mixedwith liquid propane and cooled by allowing a portion of the propanepresent to vaporize until an elevated temperature of about F. isattained, after which the mixture of residual oil and propane is mixedin agitator i6. The thoroughly agitated mass passes into decanter I8where the propane solution of oiland wax is separated from theundissolved asphalt. This oil dissolved in liquid propane, which is amixture oi paraiiinoid and non-paraflinoid oils, is chilled suficientlyto cause the wax present to precipitate out by allowing a furtherportion of the propane present to vaporize under reduced pressure. Theprecipitated .wax `is removed from the solvent solution of oil by suchmeans as cold settling, centrifuging or lter pressing; 'I'he oilsubstantially free of wax and asphalt dissolved in solvent is nexttreated with sulphuric acid introduced from tank 45. 'I'he result ofthis -treatment is to remove further quantities -of undesirable bodiespresent in the oil which tend to give the finished product an increasedviscosity temperature susceptibility. After treatment:with sulphuricacid, the oil is separated from 'the solvent and then extracted withliquid sulphur dioxide for the purpose of separating the parafiinoidfrom the non-paraflinoid constituents.

Ii desired, the oil may be extracted with liquid sulphur dioxideimmediately following the de- 'asphaltizing and dewaxing stages andsubsequent to theL separation of propane from the asphalt and wax freeoil after which the paramnoid fractions may be commingled with liquidpropane and the mixture treated with acid andclay. This procedure hasbeen described in our 4copending application No. 555,017. By performingthe acid treatment step in the-process subsequent to treatment withliquid sulphur dioxide more economical and eective results are obtainedin that the acid utilized in such treatment is free to act uponthose-undesirable bodies present in the oil which are not removable byliquid sulphur dioxide. By acid treating theI Qil prior to extractionwith liquid sulphur dioxide, a large portion of the acid is consumed inremoving from the oil unsaturated bodies which are easily removable withliquid sulphur dioxide.

If desired, the oil may be chemically treated in the presence of thepropane subsequent to deasphaltizing after which the propane isVseparated and the oil extracted with liquid sulphur dioxide, or thedeasphaltized oil may be extracted with liquid sulphur dioxide and theparafflnoid fraction chemically treated. `These procedures have beendescribed in our copendng application Serial No. 555,016.

If desired, the extraction of the deasphaltized oil with liquid sulphurdioxide may be accom-` plished in the presence of liquid propane asdescribed in our copending application Ser. No. 555,018. In such casethe temperature of the deasphaltized oil-propane mixture is further re`duced to an extraction temperature by vaporizing propane under reducedpressure. The paraffinoid fraction may then be dewaxed in the presenceof liquid propane and then chemically treated also in the presence ofliquid propane.

The foregoing description is merely illustrative of preferred modes ofcarrying out our in- `vention and is not to be taken as limiting as manyvariations may be made within the scope of the following claims bypersons skilled in the art without departing from the spirit thereof.

`We claim:

1. A process for separ'ating asphalt from oils containing the same whichcomprises commingling said oil at an elevated temperature of at 4,0least 120 F. with aliquefied normally gaseous hydrocarbon solvent andseparating said asphalt from said oil and solvent at an elevatedtemperature.

2. A process for separating asphalt from oils containing the same whichcomprises mixing said oil under superatmospheric pressure at anelenormally gaseous hydrocarbon solvent in which oil is soluble and inwhich asphalt is insoluble and separating said asphalt from said oil andsolvent. under superatmospheric pressure at an elevated perature of themixture to an elevated temperature of approximately 120 F.' andseparating asphalt from oil and solvent at said last mentioned elevatedtemperature.

6. A process as in claim 5 in which the temperature of the mixture isreduced to approximately 120 F. by vaporizing a portion of the solventunder reduced pressure.

rI. A process as in claim 1 in which the liqueed normally gaseoushydrocarbon solvent comprises propane.

8. A 'process for separating asphalt from oils containing the same whichcomprises heating said oil to an elevated temperature of at 1east 120F., mixing said heated oil While at said temperature with a liquefiednormally gaseous hydrocarbon to precipitate asphalt and separating theprecipitated asphalt from the oil and liquefied normally gaseoushydrocarbon.

9. A process as in claim 8 in which the liquefied normally gaseoushydrocarbon solvent com prises propane.

ULRIC B. BRAY. CLAUDE E. SWIFT.

vvated temperature of at least 120 F. in a liqueed

